Eyewear lens creation using additive techniques with diffuse light

ABSTRACT

Systems and methods for lens creations are disclosed. The method includes initiating light transmission from a light source through a diffuser into a container holding resin and a substrate. The light transmission is performed according to an irradiation pattern wherein each point in the resin is illuminated by at least 10% of the diffuser. This causes a lens to be formed. To achieve this illumination, at least 15% of the diffuser receives light from the light source. Further, a diameter of the diffuser is greater than or equal to a diameter of the substrate. The system performing the methods includes a polymerization apparatus and may include a resin conditioning and reservoir apparatus, a metrology unit, a resin drainage apparatus and an optional postcuring apparatus.

NOTICE OF COPYRIGHTS AND TRADE DRESS

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. This patent document may showand/or describe matter which is or may become trade dress of the owner.The copyright and trade dress owner has no objection to the facsimilereproduction by anyone of the patent disclosure as it appears in thePatent and Trademark Office patent files or records, but otherwisereserves all copyright and trade dress rights whatsoever.

RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.17/072,456, filed Oct. 16, 2020, under the same title, of which ishereby incorporated by

reference in its entirety.

BACKGROUND Field

This disclosure relates to creation of ophthalmic lenses, and, inparticular, to creating ophthalmic lenses using additive techniques.

Description of the Related Art

The current technology for producing spectacle lenses is based on a cutand polish technology called “free-form”. This process involves severalmachines: a blocker, generator, and polisher. These machines areexpensive, bulky and require a great amount of expertise to maintain. Inaddition, this technology generates a lot of waste, and requires severalconsumables, some of them toxic. Also, this technology requires a largeinventory of semi-finished lenses. It follows that setting up afree-form manufacturing facility requires a significant economicinvestment, a large workforce, and a large facility. This keeps lensmanufacturing the domain of large companies.

With the advent of 3D printing, efforts have begun to implement lenscreating using 3D printing technology. However, current 3D printingsystems for lens creation are large in size and extremely expensive.Moreover, they are very slow, requiring 15 minutes to produce one lens.Other approaches based on variations of SLA (stereo-lithography) areless expensive, but still bulky and similarly slow.

One 3D printing technology used for lens creation is known as“resin-jet”. It is based on layer-by-layer fabrication over a flatsurface. The layers are composed of small UV-curable droplets that makethe created surface smooth, which results in a surface with sufficientoptical quality. However, there are large drawbacks with resin-jettechnology. One drawback is manufacturing time. The reported printingtime for one lens with resin-jet technology is roughly one hour. Theprocess is slow because it stacks layers one by one. Further, themachine to implement resin-jet technology is large, with a bigfootprint. Plus, it is more expensive than the set blocker, generator,and polisher apparatus needed for “free-form” subtractive technology.

Another drawback of the resin-jet technology is that it only produceslenses with flat surfaces. This is problematic because spectacle lensesusually have a curved or meniscus shape. One solution is to merge twolenses with flat surface, resulting in one meniscus-shaped lenses.However, this requires two prints, which is time consuming. Plus, theresulting lens is very thick.

To move lens making into the offices of eye care professionals and makelens creation available to small business, a simple, quick andinexpensive lens creation system with a small footprint is needed.

DESCRIPTION OF THE DRAWINGS

FIG. 1A is a drawing showing a directional light beam.

FIG. 1B is a drawing showing a non-directional light beam.

FIG. 2 is a drawing showing light propagation within resin.

FIG. 3 is a drawing showing propagation of patterned light within resin.

FIG. 4 are photographs of a lens created with directional light.

FIG. 5 is a drawing showing the effect of a light diffuser ondirectional light.

FIG. 6 is a schematic drawing showing a system for monomerpolymerization for lens creation.

FIG. 7A is a schematic drawing showing a first version of apolymerization apparatus.

FIG. 7B is a schematic drawing showing a second version of apolymerization apparatus.

FIG. 8 is an image showing an input irradiance pattern.

FIG. 9 is an image showing deflection of fringe patterns.

FIG. 10 is a schematic drawing showing an exemplar metrology apparatus.

FIG. 11 is a schematic drawing showing an exemplar resign drainageapparatus.

FIG. 12 is a schematic drawing showing an exemplar post-curingapparatus.

FIG. 13 is a flow chart showing the actions taken to form a lens usingthe systems and methods described herein.

DETAILED DESCRIPTION

The methods and systems described herein describe a system for theproduction of spectacle lenses using additive techniques and lightpassed through a diffuser according to creation instructions based on awearer's prescription and usage requirements. The creation instructionsinclude specification of an irradiation pattern. According to thesystems and methods described herein, light is transmitted from a lightsource through a diffuser into a container holding resin and asubstrate. The light transmission is performed according to theirradiation pattern. The irradiation pattern includes instructionsspecifying that each point in the resin is illuminated by at least 10%of the diffuser. In some embodiments, to achieve this illumination, atleast 15% of the diffuser receives light from the light source. Further,in some embodiments, a diameter of the diffuser is greater than or equalto a diameter of the substrate. Additional details about the systems andmethods are provided below.

The methods and systems described herein describe a system for theproduction of spectacle lenses that is simpler than the current“free-form” technology. The system described herein is lightweight, haslimited movable pieces, results in less waste than “free-form”production and requires a highly reduced use of consumables whencompared to “free-form” production. This results in less expensivesystems that will enable smaller enterprises, including opticians, toenter the business of producing spectacle lenses.

To better understand the systems and methods described herein, anunderstanding of directional and non-directional light beams is helpful.FIGS. 1A and 1B provide a comparison between directional andnon-directional light beams. A directional light beam is a beam of lightfor which radiance, at any point in the beam, has non-negligible valueswithin a narrow solid angle around a single direction. Examples ofdirectional light beams are collimated beams, or spherical beams comingfrom a point source. A non-directional (or diffuse) light beam is a beamof light for which radiance, at any point in the beam, hasnon-negligible values for a finite range of directions. According to thesystems and methods described herein, nondirectional beams result fromlight passing through a light diffuser.

Referring now to FIG. 1A, a directional light beam (100A) is shown. Forany point (101A) within a directional light beam (100A), radiance isnon-negligible along a single direction (102A). In close directions(103A) radiance goes to zero or very low values, and is zero for anyother direction. Referring now to FIG. 1B, if a directional light beam(100B) passes through a light diffuser (104) the directional light beambecomes non-directional or diffuse (shown as 105), and it ischaracterized by having non-negligible radiance at a significant set ofdirections (102B), (103B) for any point within the diffuse light beam(101B). The systems and methods described herein include a diffuser toguide light to cause a polymerization reaction in resin to produceeyeglass lenses.

Polymerization of Photocurable Resins

Photopolymerization is a type of polymerization in which light is usedto initiate the polymerization reaction. It has two routes, free-radicaland ionic. Most examples in this disclosure are based on free-radicalpolymerization, but ionic polymerization can be used as well. Thereaction is triggered by a photosensitive component called theinitiator, which is mixed within the liquid monomer. Typically, thelight wavelength is in the ultraviolet range (such as, for example, UV-Aor actinic UV), although some initiators can be activated with visiblelight or other wavelengths. In some embodiments, the initiator has anabsorption band covering from 360 nm to 390 nm.

As used herein, the term “resin” refers to a mixture including a monomerbase, an initiator and, in some embodiments, an inhibitor. That is, aninhibitor is optional. The resin is in a liquid state and may includeother components, such as stabilizers, photoabsorbers, etc. Exampleresin bases include acrylate, epoxy, methacrylate, isocyanate,polythiol, thioacrylate, thiomethacrylate. Example acrylate resinsinclude pentaerythritol tetraacrylate; 1,10-decanediol diacrylate; andothers. The initiators may be free-radical or cationic. When usingfree-radical polymerization, example initiators include benzophenone,BAPO (bisacylphosphine oxides), acetophenone,1-[4-(2-Hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one(Irgacure 2959(c) from CIBA), alpha amino ketones, HAP(2-Hydroxy-2-methyl-1-phenyl-propan-1-one) and TPO(Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide), and others. Whenusing a cationic photo-initiator, example initiators are aryldiazoniumsalts, triarylsulfonium salts, ferrocenium salts, diaryliodonium salts,and others. An example inhibitor is hydroquinone.

When the initiator molecule absorbs an UV photon, the molecule isdivided into free-radicals that react with the monomer. The result ofthis reaction is a monomer attached to a free-radical, whichsubsequently reacts with more monomer molecules and creates a polymerwith growing molecular weight. The reaction finishes when thefree-radical chain end is neutralized, which typically may happen bytermination or by chain transfer to an inhibitor.

The reactions that occur during polymerization are dissociation,initiation, propagation, termination and chain transfer to an inhibitor,as represented by the following equations:

$\begin{matrix}{{{{Dissociation}{:\lbrack A\rbrack}} + I_{abs}}\overset{k_{d}}{\rightarrow}{2\left\lbrack {R \cdot} \right\rbrack}} & (1)\end{matrix}$${{{Initiation}{:\left\lbrack {R \cdot} \right\rbrack}} + \lbrack M\rbrack}\overset{k_{i}}{\rightarrow}\left\lbrack {M \cdot} \right\rbrack_{1}$${{{Propagation}{:\left\lbrack {M \cdot} \right\rbrack}_{n}} + \lbrack M\rbrack}\overset{k_{p}}{\rightarrow}\left\lbrack {M \cdot} \right\rbrack_{n + 1}$${{{Termination}{:\left\lbrack {M \cdot} \right\rbrack}_{n}} + \left\lbrack {M \cdot} \right\rbrack_{m}}\overset{k_{t}}{\rightarrow}\lbrack M\rbrack_{n + m}$${{{Chain}{transfer}{to}{an}{inhibitor}{:\left\lbrack {M \cdot} \right\rbrack}_{n}} + \lbrack Z\rbrack}\overset{k_{z}}{\rightarrow}\left\lbrack {M_{n}Z} \right\rbrack$

Here [A] is the initiator concentration, [R.] is the free-radicalsconcentration, [M] is the monomer concentration, [M.]_(i) is an active(with attached free-radical) polymer composed of i monomers, [M]_(i) isa stable polymer composed of i monomers, [Z] is the concentration of aparticular inhibitor that may be present and [M_(n)Z] is theconcentration of polymer that reacted with the inhibitor. Parametersk_(d), k_(i), k_(p), k_(t), and k_(z) are the kinetic constants for eachreaction. I_(abs) is the amount of UV radiation energy absorbed by theinitiator.

These reactions are generally solved under the assumption of steadystate, where the free radicals generated by the dissociation of thephotoinitiator are consumed by polymerization termination (bothrecombination and inhibition). The rate of change of the monomerconcentration is given by the following equation:

$\begin{matrix}{\frac{d\lbrack M\rbrack}{dt} = {{- {k_{p}\lbrack M\rbrack}}\frac{{\lbrack Z\rbrack k_{z}} - \sqrt{{\lbrack Z\rbrack^{2}k_{z}^{2}} + {16\phi I_{abs}k_{t}}}}{4k_{t}}}} & (2)\end{matrix}$

In this formula, the inhibitor concentration [Z] might depend on time.The variable ϕ indicates the initiator quantum efficiency. Also, k_(z),k_(t) and k_(p) depend on the temperature through the Arrheniusrelation. For example, for k,

$\begin{matrix}{{k_{p} = {k_{po}e^{- \frac{E_{p}}{RT}}}},} & (3)\end{matrix}$

where k_(po) is a constant, E_(p) is the energy involved in thepropagation reaction and R is the gas constant. Because the polymerpropagation reaction is exothermic, it is expected the kinetic constantschange over time.

Solving the differential equation (2) requires numerical integrationalgorithms, but under some approximations, analytic solutions illustratethe methods described herein. In a applying the methods describedherein, numerical solutions to equation (2) can be used, and dependingon the required accuracy, approximate analytical solutions can also beused. When there is no inhibitor and the temperature is constant, themonomer concentration over time is given by the following equation:

$\begin{matrix}{{{\lbrack M\rbrack(t)} = {\left\lbrack M_{0} \right\rbrack e^{{- k_{p}}t\sqrt{\frac{\phi I_{abs}}{k_{t}}}}}},} & (4)\end{matrix}$

where M₀ is the initial monomer concentration. The polymer created atthe same time as the monomer is consumed during polymerization. Thedegree of conversion c is the proportion of monomer converted intopolymer shown by the equation:

$\begin{matrix}{c = \frac{{\lbrack M\rbrack(t)} - \left\lbrack M_{0} \right\rbrack}{\left\lbrack M_{0} \right\rbrack}} & (5)\end{matrix}$

When the conversion rate increases, the viscosity of the mediaincreases. When the conversion reaches a certain point called thecritical conversion c_(cr), the viscosity increases exponentially, andthe mixture solidifies due to the low mobility of the large polymermolecules and/or high density of crosslinks between polymer chains.

When directional light is applied to the photocurable resin, theirradiance absorbed per unit length by the initiator after propagationthrough a depth z in the resin, is obtained from the Lambert-Beer lawaccording to this equation:

I _(abs) =[A]I ₀ αe ^(−[A]αz−γz)  (6)

Here α is the molar absorption coefficient of the initiator, z is thedepth inside the material, γ is the absorption coefficient of the resinwithout the initiator and I₀ the input intensity. As such, theabsorption is maximum at the beginning of the material and decaysexponentially inside.

When a resin in a container is irradiated with directional light, thepolymerization rate is faster closer to the material interface and willdecay exponentially inside the material. At a given time a certain partof the material will reach the critical conversion as depicted in FIG. 2. All material below this point will be a solid and all material aboveit will be a liquid. We call this frontier the “polymerization front”shown as 240. Referring now to FIG. 2 , light 200 propagation passingthrough a transparent substrate 220 inside a container 210 holding resin230 is shown. The dashed line 250 represents surfaces with the sameirradiance.

During light exposure, the polymerization front propagates withlogarithmic speed inside the resin 230. When the exposure is stopped, alayer whose thickness depends on exposure time results. The thickness ofthe cured material is given by the equation:

$\begin{matrix}{{T(t)} = {\frac{1}{\lbrack A\rbrack\alpha}{\ln\left( \frac{\lbrack A\rbrack I_{0}\alpha k_{p}^{2}\phi t^{2}}{k_{t}{\ln\left( {1 - c_{cr}} \right)}^{2}} \right)}}} & (7)\end{matrix}$

This equation (7) can only be applied with directional light when allparameters are constant with time.

When the projected light is patterned, the shape of the polymerizationfront follows the radiance pattern, as shown in FIG. 3 . FIG. 3 showsthe light 300 propagation through the resin 330 in a container 310.Here, the light is directional but presents a transverse distributionwhich modifies the shape of the polymerization front 340 as well as theshape of the surfaces with same irradiance 350.

When the combination of exposure time and input UV irradiance patternare correctly calibrated, the shape of the polymerization front can becontrolled according to equation (7) and more precisely by numericalintegration of equation (2). This technique can be used to make avariety of three-dimensional objects. However, the resultingthree-dimensional objects typically lack transparency and opticalquality because of self-focusing, as explained below. For this reason,this technique alone, which uses directional light, is not enough tomake spectacle lenses.

As used herein, “spectacle lens” refers to any type of eyewear that isworn a small distance from the wearer's eye. Spectacle lenses caninclude: spherotorical lenses, aspherical lenses, progressive additionlenses, bifocals, trifocals, lenticulars, slab offs, etc. The typicalspectacle lenses made may be from 40 to 80 mm in diameter and have athickness of from 2 to 8 mm. The systems and methods described hereinmay also be used to make larger and smaller lenses, as well as thinnerand thicker lenses.

The systems and methods described herein are used to create spectaclelenses which may have fixed surfaces or free-form surfaces. For a fixedsurface lens, the lens is produced from resin that adheres to thesubstrate. As shown in FIGS. 2 and 3 , the fixed surface of thesubstrates 220 and 320 are flat, but the substrate can have any shape.The most convenient substrate shape for spectacle lenses is a sphericalsurface. However, more complex substrate surfaces can be used, such asaspherical, torical, atorical, multifocal, etc. In some embodiments,electronic circuits or image formation systems can be embedded insidethe substrate. In other embodiments, the substrate is constructed oraugmented to allow for the productions of lenses with large edgethickness. In one such embodiment, the substrate may be aspherized,lenticularized toward the edge to increase the amount of resin that canbe held. In another such embodiment, a cylindrical wall is attached tothe substrate edge to increase the amount of resin that can be held. Thesubstrate can be made of polycarbonate, allyl diglycol carbonate,polyurethane-based plastic, glass, or similar materials, and may beCR-39® or TRIVEX® available from PPG Industries Ohio, Inc. of Cleveland,Ohio.

In the embodiments described herein, the fixed surface represents thesurface that is farthest from the eye. In other embodiments, the ordercan be reversed such that the fixed surface represents the surface thatis closest to the eye. The free-form surface is the surface determinedby the location of the polymerization front. In the followingembodiments, the free-form surface is the surface closest to the eye.

Self-Focusing

As described above, a directional light beam with adequate distributionof irradiance may be used to create a controlled polymerization front inresin, so the shape of the free-form surface provides the desiredspectacle lens. However, directional light beams are prone to createstrong defects in the polymerized materials because of what is known asthe self-focusing effect. The refractive index of the polymer istypically slightly larger than the refractive index of the liquid resin.Any minute deviation of the local value of the irradiance impinging onthe liquid resin, (the deviation can be present on the profile as noise,which is inevitable in directional light, can be due to dust particlesor defects on the transparent surfaces holding the resin, and can resultfrom the pixel structure of the projector) will cause a local variationof the refractive index that in turn will locally focus the irradiance.This creates a positive feedback loop that produces a distinctivedefect, typically in the form of the shape of a needle oriented alongthe direction of propagation of the radiance. As a result, the generatedpolymer loses transparency, and the free-form surface becomes spiky suchthat the resulting object has no or poor optical quality. This is shownin the images of a lens created with directional light in FIG. 4 inwhich 410A is a top view and 410B is a perspective view. To overcomethis, the methods and systems described herein use diffused lightinstead of directed light.

Light Diffuser

When a light diffuser is placed between a light projector and resin, thelight from each radiant pixel is scattered into multiple angles suchthat the light does not follow the initial direction from the projector.(See the discussion of FIGS. 1A and 1B above.) To implement the methodsdescribed herein, it is preferable to have a diffuser with properties asclose to conforming to Lambert's cosine law as possible. As describedbelow, the properties of the diffuser are evaluated to measure how closeto the ideal/Lambertian the diffuser is using a bidirectionaltransmission distribution function (BTDF). For an ideal diffuser, theradiance follows Lambert's cosine law. Measurements using BTDF are takento evaluate the properties of the diffuser. The diffuser is made fromlight diffusing materials which include glass and polymers manufacturedwith light diffusing additives. More specifically, the diffuser may bemade from opal glass, white glass, acrylate sheets with calciumcarbonate additives, and others. In one embodiment, an example lightdiffuser is an acrylate sheet that is 2 mm thick and is made with 3.3 wt% CaCO₃ additive.

Referring now to FIG. 5 , there is shown a schematic drawing showing theimpact of light diffuser 501 on light 502. The light source 500 sendsradiant energy (that is, light) 502 toward diffuser 501. The lightsource 500 may be, for example, an ultraviolet Digital Light Processing(UV DLP) projector or a scanned UV laser. For example, the projector 500may emit radiation (that is, UV light) with a peak at 385 nm. The lightemitted 502 by the source is highly directional. The diffuser 501scatters light in all directions, so any point Q on the diffuser willemit light in all directions. The radiance of the scattered light isdependent on the bidirectional transmission distribution function of thediffuser. Hence, the flux reaching any point P behind the diffuser hascontributions 503 from multiple points on the diffuser.

According to the systems and methods described herein, the diffuser islocated inside and preferably at the bottom of a container, vat orchamber of resin. When the diffuser is located at the bottom of acontainer filled with resin, every point within the resin receives lightfrom multiple points on the diffuser and from multiple directions. Inone embodiment, each point in the resin receives light from at least 10%of the diffuser area. As such, the light transmitted from the diffuserto and through the resin is not directional, eliminating theself-focusing problem described above. To achieve this—that is, so thatevery point in the resin receives light from multiple source locationson at least 10% of the diffuser—a substantial part of the diffuser isilluminated. Specifically, in some embodiments, at least 15% of thediffuser area is illuminated by a light source. If this does not occur,the self-focusing will remain or not be fully removed. Using the methodof at least 15% illumination of the diffuser to illuminate each point inthe resin with at least 10% of the light from the diffuser results in apolymerized lens with a free-form surface this is smooth, transparentand having low haze. The resulting lens has good optical quality. Anadvantage of this technique is that the system is tolerant to dust, dirtor any imperfections in the projector or the media between the projectorand the resin container.

Controlling the Shape of the Polymerization Front

To create desired eyeglass lenses, the shape of the polymerization frontmust be controlled. A precise model of the polymerization inside acontainer of resin takes into consideration each of the following:

-   -   Irradiance propagation from the diffuser to the substrate and        into the lens.    -   Temporal evolution of polymer, initiator, and inhibitor        concentration.    -   Heat diffusion and temporal evolution of temperature.    -   Monomer, initiator, and inhibitor diffusion.    -   Bidirectional transmission distribution function (BTDF) of the        light diffuser.

When using diffuse light, equation (7) no longer applies. Also, equation(3) cannot be applied when parameters such as reaction rates, initiator,or inhibitor concentrations changes over time. Therefore, a carefulmodeling of the reactions (1) is needed when using diffuse light.

The desired shape of the free-form lens surface may be referred to asz_(L)(x,y). The differential equations corresponding to equations (1)are numerically solved for a given input irradiance pattern I to obtainthe polymerization front z_(P)(x,y,I). For a fixed set of control points(x_(i), y_(i)) the following merit function is computed:

$\begin{matrix}{{M(I)} = {\sum\limits_{i}{w_{i}\left\lbrack {{z_{P}\left( {x_{i},y_{i},I} \right)} - {z_{L}\left( {x_{i},y_{i}} \right)}} \right\rbrack}^{2}}} & (8)\end{matrix}$

The merit function is minimized with respect to the parameters definingthe input irradiance pattern or “input pattern” for short. When thelight source is a DLP, the irradiance pattern impinging on the diffuseris defined pixel-wise and is represented as a matrix I_(nm), where theindices n and m run over the rows and columns of the digital image.Other merit functions may be used, such as the sum of the differencesbetween the curvatures of the target (the free form surface) and thepolymerization front.

During the process of monomer polymerization, the input patterns I_(nm)can be modified with the information provided by one or more sensors orsensor systems which are used to measure the resin in the container andthe polymerization front as it grows. This real-time close-loop processallows for tight control of the polymerization front and avoids orcancels instabilities that could affect its shape. The sensors andsensor systems used in the polymerization process include one or more avisual inspection system (VIS) camera, an infrared (IR) camera, anultrasound topography system, a tomography system, a moiré topographysystem, an interferometric topography system, temperature sensors, andother similar devices and systems. These techniques are used in thepolymerization apparatuses shown in and described regarding FIGS. 7A and7B below and the metrology system described below and shown in FIG. 10 .

Description of System and Constituent Apparatus

The lens producing system described herein includes, but is not limitedto, the following components:

-   -   Resin conditioning and reservoir apparatus,    -   Polymerization apparatus,    -   Metrology apparatus,    -   Resin drainage apparatus, and    -   Postcuring apparatus.

Resin Conditioning and Reservoir Apparatus

The creation and evolution of the polymerization front depends onmultiple parameters, as described above. For this reason, tight controlover the resin formulation is maintained. The resin includes acombination of inhibitor and photoinitiator. The inhibitor andphotoinitiator must be stored and used at particular temperatures.

One inhibitor of chain photopolymerization reactions is oxygen. Theoxygen may be diffused inside the resin from the surrounding air, aprocess that produces a concentration gradient inside the resin. Thisgradient could result in an inhomogeneous resin that might disrupt theshape of the polymerization front. For this reason, the concentration ofany inhibitor inside the resin, including oxygen, must be kept at aknown appropriate and constant level. The components of the resin mustbe homogeneous before an input pattern is projected.

To achieve a homogeneous resin having an appropriate concentration ofoxygen, some of the possible options are:

-   -   Store the resin in container with an oxygen-free atmosphere (for        example nitrogen).    -   Use an oxygen scavenger that is compatible with the resin.    -   Saturate the resin with oxygen.    -   Saturate the resin with a gas with a certain percentage of        oxygen (for example air), which ensures a constant concentration        of oxygen below saturation.    -   De-gas the resin.

A resin conditioning and reservoir apparatus is used to hold the liquidresin and maintain its chemical composition in an appropriate andconstant state. One embodiment of a resin conditioning and reservoirapparatus 600 is shown in FIG. 6 . The liquid resin 601 is held inside aclosed tank 602. A set of sensors, actuators and pipes that run in andout of the tank with corresponding valves and pumps are controlled bycontroller 613 that includes electronics and software. A mixingmechanism 603 is provided in the tank 602 to actuate, stir and/or mixthe components of the resin so the components of the resin are keptthoroughly mixed and uniformly distributed. Oxygen, clean and dry air,or any preferred mix of gases can be pumped or bubbled into the resinthrough conduit 607 to increase solubility and help mixing. Also, apreferred gas can be introduced in the tank 602 to control the partialpressures of each gas in the atmosphere inside the chamber through pipe608. A venting mechanism is provided to allow for changes in thecomposition of the atmospheric component inside the tank, and to controlinternal pressure. The venting mechanism may include componentsincluding pipes, valves and pumps. In the embodiment shown in FIG. 6 ,the venting may be achieved with pipe 606A and 606C and valve 606Bconnected with and controlled by controller 613. Sensors 604 areincluded in the tank 602. In one embodiment, a typical sensor arrayallows for measuring physical and chemical parameters such astemperature, oxygen concentration, nitrogen concentration, and the like.Either or both pipe 608 and/or 606A may be used to create a vacuuminside the tank to degas the resin. An oxygen scavenger mechanism (notshown) may optionally be included in the tank to degas the resin. Aheater 605 may be included in the tank 602 to control temperature of theresin 601. The pipe 609 is used to extract the resin and deliver it to apolymerization apparatus like those shown in FIGS. 7A and 7B, describedbelow.

A filtering system 610 consisting of a pump/valve mechanism and a filteris connected to the tank 602 to remove particles that would interferewith production of lenses, impeding lens formation and/or reducing lensquality. In one embodiment, particles having size above 0.5 microns areremoved by the filtering system 610. In addition, the filtering system610 may remove gel-type polymer formed by spontaneous polymerization orduring the printing process. The filtering system 610 may workpersistently in a closed loop or at specified time intervals, dependingon the particular characteristics of the resin and the polymerizationprocess. The filtering system may be coupled to and controlled bycontroller 613.

A resin recovery system 612 may be included in the resin conditioningand reservoir apparatus 600. Remnants of liquid resin from previouspolymerization processes may be poured into tank 612, filtered viafilter 611 and incorporated into the conditioning and reservoirapparatus. Concentration of initiator and inhibitors can be measured inthe remnants of resin (for example, by means of well-known spectroscopictechniques) prior to introducing the remnants to the tank 612 or as theresin seats on the tank. Concentration of the components of the resinmay be adjusted by adding appropriate amounts of inhibitor, initiatorand/or monomer/oligomer prior to the introduction of the resin into theconditioning/reservoir tank 602.

Polymerization Apparatus

Referring now to FIGS. 7A and 7B, two exemplary embodiments of apolymerization apparatus are shown. The polymerization apparatus iscomposed of a chamber 700A/700B where resin 702 is placed is such a waythat UV light passes through the bottom glass plate 705, the opticaldiffuser 704A/704B, and the substrate 701 and irradiates the resin 702.Formation of a lens occurs inside the polymerization apparatus. Thechamber 700A/700B holds and encloses the components required to achievethe polymerization except for the UV source 708. The top 711 and bottom705 are glass plates or other appropriate transparent material. Withinthe chamber 700A/700B, a substrate 701 sits in a bed, table, groovedarea or other supportive structure (not shown) and/or or may be held inplace by clips, tabs or other fastening device (not shown) to the wallsor extensions to the walls of chamber 700A/700 B. Resin 702 is poured inthe concave part of the substrate 701. Curing radiation (that is, UVlight) 709 is emitted from the light source 708. The light source 708may be a scanning laser or a DLP. Curing radiation passes through thebottom transparent plate 705 and is diffused by optical diffuser704A/704B. Diffused light then propagates through the substrate 701 andenters the resin 702, where the lens 703 is formed.

In both embodiments of the polymerization apparatus shown in FIGS. 7Aand 7B, the gaseous atmosphere and pressure inside the chamber 700A/700Bis controlled through venting components including input/output pipes706 and 707. These pipes direct nitrogen, oxygen, air, a mix of thesegases and/or other gases into the interior of the chamber 700A/700B.These pipes may also be used to create a vacuum inside the chamber todegas the resin 702. The venting component includes valves and pumps aswell as pipes 706 and 707 for the input and output of gases. The valvesand pumps of the venting components and the light source are controlledby controller 710. The appropriate selection of gases depends on theresin formulation. For example, an acrylic resin with a 50% mix ofmonofunctional and bifunctional monomer and a mix of initiator at 0.5%and inhibitor at 1% can be used. In this example, as there is aninhibitor, oxygen is removed from the conditioning and reservoirapparatus 600 and will also be removed from the polymerization chamber700A/700B by venting nitrogen into the chamber. Polymerization may beperformed in a low-pressure nitrogen atmosphere to avoid the creation ofbubbles within the polymerized lens 703.

In operation, as curing radiation enters the resin 702 through the glassplate 705, a polymerization front is created that separates the liquidresin 702 from the polymerized part that becomes lens 703. Aspolymerization proceeds, the polymerization front moves away from thesubstrate surface, and the growing lens thickens.

The irradiance pattern emitted by light source 708 used to create theformed lens 703 is computed using equation (1) (described above) and theBTDF of the diffuser 704, which provides the volumetric density ofcuring photons inside the resin. When the thickness of the formed lens703 reaches the target value, the polymerization front will have theshape of the target surface, according to the optimization algorithm (8)(described above), the lens is completed, and the light source 708 isturned off.

In the embodiment shown in FIG. 7A, the diffuser 704A is flat and islocated above and adjacent to the bottom 705. In the embodiment shown inFIG. 7B, the diffuser 704B is curved, having similar curvature of theconvex side of the substrate 701. Further, in the embodiment shown inFIG. 7B, the diffuser 704B is located below and adjacent to thesubstrate 701. In one embodiment, the curved diffuser 704B may beconstructed from transparent resin having light dispersing additives,such as calcium carbonate, glass, titanium. In some embodiments, thelight dispersing additive has particles sized between 1 and 3 microns.It is preferable that the diameter of the diffuser 704A/704B is greaterthan or equal to the diameter of the substrate 701. That is, it ispreferable that the diameter of the diffuser 704A/704B is not smallerthan the diameter of the substrate 701.

In variations of these embodiments, the space between the substrate 701and the diffuser 704A in the embodiment shown in FIG. 7A, or between thediffuser 701 and the bottom plate 705 in the embodiment shown in FIG.7B, may be filled with a substance, preferably a liquid, to ensure indexmatching between the different surfaces to eliminate or reduce thereflection in these surfaces. This index matching liquid has theproperties of being transparent and having a refractive index close toor matching that of the substrate and the diffuser. In one embodiment,when the substrate is CR-39® and acrylate is the diffuser, the indexmatching fluid glycerin (having a refractive index of 1.47) may be used.

In some embodiments, the upper window glass 711 is removed.

Referring now to FIG. 8 , an example of a possible input light pattern800 applied via the polymerization apparatus shown in FIG. 7A is shown.This pattern may be projected for 60 seconds, or other appropriate time,to produce a polymerization front with varying curvature to create lens703 as a progressive addition lens. Referring now to FIG. 9 , the lens900 resulting from application of the methods described herein using thepolymerization apparatus shown in FIG. 7A with the input pattern shownin FIG. 8 is shown.

Metrology Apparatus

An additional module can be attached to the polymerization apparatusshown in FIGS. 7A and 7B to make real time measurements and to providefeedback to correct or improve the light input pattern during thepolymerization process. Referring now to FIG. 10 , an embodiment of ametrology apparatus 1000 is shown. Included in the metrology apparatus1000 is the polymerization apparatus shown in FIG. 7A. In thisembodiment, the polymerization apparatus from FIG. 7A is used withoutthe upper glass 711. The metrology apparatus 1000 includes a thermalcamera 1005 to monitor in real time the temperature distribution of theresin 702 by sensing thermal radiation 1006 in the resin 702. Aspolymerization is an exothermic reaction, the light input pattern, whichis spatially dependent, produces a higher rate of polymerization whereit provides a higher photon density. Accordingly, the light inputpattern, the shape of the polymerization front over time, andtemperature distribution in the resin are correlated. Unexpectedvariations in the temperature distribution in the resin will similarlycorrelate with lack of homogeneity of the resin, with the presence ofgel-type precipitates, or other impurities. To use a thermal camera1005, the top glass plate of the polymerization chamber is removed as itis opaque to thermal radiation 1006.

In some embodiments, the metrology apparatus 1000 includes an additionalsecondary system is used to monitor the shape of the polymerizationfront as it evolves during the polymerization process. This secondarysystem evaluates topography with ultrasonic waves.

Referring again to the metrology apparatus 1000 in FIG. 10 , an opticalsystem is depicted using camera 1004. Camera 1004 uses low-wavelengthlight that cannot polymerize the resin to evaluate the formation of thelens and/or the polymerization front. For example, the camera 1004 mayuse red light with a wavelength of 635 nm, or near-infrared light with awavelength of 780 nm. The camera 1004 may use light having otherwavelengths that do not interfere with polymerization of the resin. Inone embodiment of the metrology apparatus, a projector of structuredlight projects fringe patterns to shine structured low-wavelength lightfrom above to the resin 702, and a camera 1004 images the lightreflected from the polymerization front. The polymerization frontreflects due to the variation of refractive index between the liquidresin and the polymer.

The metrology apparatus 1000 may include, additionally or alternatively,a light source 1002 to send structured low-wavelength light beam 1003from below. This may be accomplished by transmission of a measuringlight beam 1003 through the lens 703 which is detected with camera 1004.In this embodiment, the measuring light beam 1003 and the curing light709 are mixed by a beam-splitter 1001, for example a dichroicbeam-splitter that will not affect the amount of curing light projected.

Other embodiments of the metrology apparatus 1000 may include other oradditional sensors, such IR cameras, ultrasound sensors, and others.

Resin Drainage Apparatus

After the lens has been formed by the polymerization apparatus,remaining resin may be drained and reused. More specifically, after thepolymerization apparatus has completed the target shape and formed thelens with the target thickness, the projector is turned off andprojection of the input pattern stops. The substrate containing the lensand remaining non-polymerized resin are then removed from thepolymerization apparatus. This can be achieved manually or using anautomated system. After the lens is completed, the remaining liquidresin is removed or otherwise drained from the polymerization apparatusto avoid unwanted polymerization of the resin.

Referring now to FIG. 11 , an exemplary resin drainage apparatus 1100 isshown. The substrate 1116 with the formed lens 1114 and remaining liquidresin 1112 are placed and firmly attached to a base 1110 and placed on aspinning machine 1101. The base 1110, substrate 1116, lens 1114 andremaining resin 1112 are rotated by spinning machine 1101. Thecentrifugal force moves the remaining liquid resin away and off the lens1114 and substrate 1116, and into the receptacle formed by a cone-shapedshelf 1102. The speed of the spinning machine 1101 along with theviscosity of the resin 1112, which in turn is largely dependent on thetemperature, determines the amount of resin remaining on the lens. Thecover 1103 blocks resin from flying out of the resin drainage apparatus1100. The resin collected by the spinner on top of the cone-shaped shelf1102 is recovered with drain pipe 1120 to be recycled and reused asdescribed (above) regarding FIG. 6 . The collection of remaining resinfor recycling and reuse can be done automatically, the resin beingpumped from drain pipe 1120 from the resin drainage apparatus 1100 ofFIG. 11 to the system of FIG. 6 .

When the volume of remaining resin is large, excess resin can be dumpedbefore spinning by tilting the substrate. For those resin formulationsin which the amount of gelified resin is too large, the remaining resincan be discarded, and appropriate solvents can be used to remove thenon-cured resin from the substrate-lens pair.

In another embodiment, after the resin has drained through pipe 1120, aprecure of the thin layer of liquid resin remaining on top of the lenssurface can be achieved via a diffuse UV light source 1104 included onthe underside of the cover 1103. According to this embodiment, when thislayer is precured, a small amount of liquid hard coating lacquer can bepoured on the lens via applicator 1105 which may be integrated into thecover 1103. The lacquer can be spun off by an additional rotation cycleof the spinning machine 1101, leaving a uniform layer than can befurther photocured or thermally cured by means of heaters (not shown)that may be included in resin drainage apparatus 1100.

Post-Curing Apparatus

Depending on the formulation and properties of the resin and relatedprocess parameters for a particular lens, post curing actions may beperformed. Referring now to FIG. 12 , an embodiment of a post-curingapparatus 1200 is shown. The post-curing apparatus 1200 may be usedafter remaining liquid resin has been drained in the spinner-type resindrainage apparatus 1100 of FIG. 11 . In some embodiments, the resindrainage apparatus 1100 does not incorporate UV sources and/or thermalsources, so the film of liquid resin left on top of the formed lensafter performing actions using the resin drainage apparatus 1100 must becured using another apparatus. In particular, the resin drainageapparatus 1100 may lack a venting system that would provide oxygen-freeatmosphere. In that case, the thin layer left on top of the lens cannotbe cured, as it is a few microns thick and oxygen is continuouslydiffusing from the atmosphere. In that case, an additional apparatus maybe needed, a post-curing apparatus.

Referring to FIG. 12 , the post-curing apparatus 1200 includes a chamber1212 into which the substrate 1217 and the lens 1215 are placed with asealed lid 1201 transparent to UV radiation. Input and output pipes1202A and 1203A are included through the walls of the chamber 1212 withcontrol valves 1202B and 1203B to allow for the maintenance and controlof the appropriate atmosphere (that is, gaseous mix) within the chamber1212. Depending on the resin, a neutral nitrogen atmosphere may be usedat high pressure to avoid bubble formation on the lens 1215. If theresin is properly degassed, low pressure nitrogen or a vacuum can beused to expel the oxygen from the resin. After the atmosphere within thechamber 1212 and the lens 1215 are free from oxygen, a source 1204 ofcuring radiation 1205 (for example, a UV light source) is activated tocure the remaining layer on the lens 1215. Heaters 1216 may optionallybe included and integrated with the bottom of the chamber 1212. Theheaters 1216 may be used to improve mobility of the non-reacted monomerinside the polymer matrix and increase the degree of conversion c (seeEquation 5 above).

A diffuser 1206 may be incorporated in the lid 1201 to homogenize theirradiance 1205 reaching the thin layer of liquid resin on the lens 1215from the light source 1204.

Output Product—A Lens

The output product of the systems and methods described herein is alens, namely a substrate/formed-lens composite. In some cases, theformed lens will be detached from the substrate and the formed lens willbe the final lens. In other cases, the formed lens will not be separatefrom the substrate, such that the two components together form theeyewear lens. In this second case, the eyewear lens might have someoptical properties inherited from the substrate. For example, thesubstrate can be polarized, tinted or photochromic, so long as asufficient amount of curing radiation can pass through the substrate topolymerize the forming lens. The substrate may also incorporate anantireflective coating or hard coating on its convex surface. Further,the substrate may provide power. Combining a substrate with the formedlens provides great advantages as it allows to for the production ofspectacle lenses not limited to the optical properties of thepolymerized resin.

In another embodiment the formed lens is detached from the substrate.The resulting product is the formed lens comprised entirely ofpolymerized resin. The advantage of this embodiment is that thesubstrate can be reused.

The Method

Referring now to FIG. 13 , the method 1300 used to produce a spectaclelens using the apparatuses and methods described above is shown.Referring to block 1301, an input job is received. The input jobincludes information required for manufacturing a lens, including:geometry of the free-form surface, expected or preferred thickness,geometry of the fixed surface, expected or desired refractive index,lens diameter or contour shape, user parameters, user lifestyleparameters, and others. The input job specification may include some orall of the information listed. As used in the input job, user parametersinclude nasopupilar distance; frame properties such as framepantoscopic, wrapping angle, frame vertex distance; fields of view;reading distance; working distance; age; health; and other parameters.As used in the input job, user lifestyle may be specification of theprimary activity or activities of the user, including sports—outdoor,indoor, a specific sport such as swimming and running—driving, reading,desk job, and/or a career, such as, for example, chef, teacher, lawyer,bus driver, etc.

Upon receipt of the input job, lens creation instructions aredetermined. The lens creation instructions (or requirements) include aninput pattern for UV light and a resin composition. The irradiationpattern or input pattern is calculated (as shown in block 1302) suchthat the polymerization front for a given exposure time coincides withthe desired geometry of the free-form lens surface. This calculation ofthe input pattern consists of an optimization process for every pointinside the resin to be irradiated by multiple points from the diffuser.

Specifically, the calculation begins with the lens surface specified inthe input job. The input pattern of light is calculated such that thepolymerization front after a time “t” coincides with the objectivesurface including evaluation of the following.

-   -   a. The diffuser receives the directional light from the light        source, and each point of the diffuser emits in each direction        according to its BTDF function.    -   b. Each point in the resin receives light from multiple source        locations in the diffuser.    -   c. The light received by the resin initiates the photochemical        reactions described in Equation 1.    -   d. The photochemical reactions change the degree of conversion        pursuant to Equation 5 at each point in the resin.    -   e. The polymerization front is defined as the points inside the        resin that reach a degree for conversion c equal to the critical        conversion value.

During the calculation (1302), resin composition is also determined suchthat the creation instructions include the irradiation pattern and resincomposition. The resin composition defines the composition of the resin.The calculation (1302) also determines the amount of liquid resin thatwill be needed to create the formed lens with the needed diameter. Thecomposition of the resin includes particular amounts of photo-initiatorand inhibitor (optional) depending on the information in the input job.For example, lenses with greater thickness might require less lightabsorption which is obtained with less photo-initiator or a largeramount of inhibitor. This is why the creation instructions includedetermination of both the irradiation pattern and the resin composition.Then, resin is conditioned and stored according to the proceduredescribed above regarding FIG. 6 (as shown in block 1303). Thecomposition of the resin can be adjusted to meet the requirements of thecreation instructions by changing the concentration of photo-initiatorand/or inhibitor.

Next, polymerization is performed (as shown in block 1305). Thepolymerization begins with placing a new clean substrate in thepolymerization chamber, followed by pouring the resin (according toblock 1304) into the polymerization chamber. The polymerizationcontinues with radiating the diffuser with the input pattern thatprovides the correct photon density distribution within the resin toachieve the lens surface specified in the input job according to theirradiation pattern in the creation instructions. During thepolymerization (1305), the information from the metrology apparatus maybe used to adjust and/or correct the input patterns (as shown in block1309).

Once the formed lens is created in the polymerization chamber, the resinis drained from the polymerization chamber (as shown in block 1306),resulting in an object composed of the substrate and the formed lenscovered by a gel layer.

During post-curing (as shown in block 1307), the gel layer ispolymerized. The formed lens may then be detached from the substrate.The result is an eyewear lens (as shown in block 1308). In someembodiments, when the formed lens is not detached from the substrate,the output product is the composite of the substrate and the formedlens.

After removal, the formed lens may be cut before placing the lens in aframe for wearing. Other actions may be taken on the formed lens, suchas applying an antireflective coating or hard coating.

CLOSING COMMENTS

Throughout this description, the embodiments and examples shown shouldbe considered as exemplars, rather than limitations on the apparatus andprocedures disclosed or claimed. Although many of the examples presentedherein involve specific combinations of method acts, apparatuses,components or system elements, it should be understood that these may becombined in other ways to accomplish the same objectives. With regard tomethods, processes and flowcharts, additional and fewer actions may betaken, and the actions as shown and described may be combined or furtherrefined to achieve the methods described herein. Acts, components,apparatuses, elements and features discussed in connection with oneembodiment are not intended to be excluded from a similar role in otherembodiments.

As used herein, “plurality” means two or more. As used herein, a “set”of items may include one or more of such items. As used herein, whetherin the written description or the claims, the terms “comprising”,“including”, “carrying”, “having”, “containing”, “involving”, and thelike are to be understood to be open-ended, that is, to mean includingbut not limited to. Only the transitional phrases “consisting of” and“consisting essentially of”, respectively, are closed or semi-closedtransitional phrases with respect to claims. Use of ordinal terms suchas “first”, “second”, “third”, etc., in the claims to modify a claimelement does not by itself connote any priority, precedence, or order ofone claim element over another or the temporal order in which acts of amethod are performed, but are used merely as labels to distinguish oneclaim element having a certain name from another element having a samename (but for use of the ordinal term) to distinguish the claimelements. As used herein, “and/or” means that the listed items arealternatives, but the alternatives also include any combination of thelisted items.

It is claimed:
 1. A method for creating a lens, the method comprising:receiving input information including a lens prescription; calculatingcreation instructions based on the input information, the creationinstructions including: 1) an irradiation pattern, and 2) an exposuretime to use a light transmission of the irradiation pattern to form alens having the lens prescription; initiating the light transmission ofthe irradiation pattern from a light source through a diffuser into acontainer holding resin held within a substrate, wherein each point in athickness of the resin sufficient to form the lens is illuminated by atleast 10% of an area of the diffuser; and stopping the lighttransmission after the exposure time to form the lens, wherein the lensmeets the creation instructions, wherein a single polymerization fronthas the shape of a target surface of the lens that meets the creationinstructions, wherein the substrate is selected from the group includingpoly(allyl diglycol carbonate), polycarbonate, polyurethane-basedplastic or glass.
 2. The method of claim 1 wherein at least 15% of thearea of the diffuser receives light from the light source.
 3. The methodof claim 1 wherein a diameter of the diffuser is greater than or equalto a diameter of the substrate.
 4. The method of claim 1 furthercomprising draining the container of the resin.
 5. The method of claim 4further comprising spinning the formed lens to remove remaining resin.6. The method of claim 4 further comprising applying heat and/or lightto the formed lens to complete curing of the formed lens.
 7. The methodof claim 4 further comprising removing the formed lens from thesubstrate.
 8. The method of claim 1 wherein the creation instructionsinclude 3) a resin composition.
 9. The method of claim 1 wherein theresin composition includes specific amounts, portions or concentrationsof an inhibitor, a photo initiator, and a monomer or oligomer.
 10. Themethod of claim 9 wherein the monomer is selected from the groupincluding acrylate, epoxy, methacrylate, isocyanate, polythiol,thioacrylate, thiomethacrylate.
 11. The method of claim 9 wherein theinhibitor is selected from the group including: oxygen and hydroquinone.12. The method of claim 9 wherein the photo initiator is selected fromthe group including: benzophenone, BAPO (bisacylphosphine oxides),acetophenone,1-[4-(2-Hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, alphaamino ketones, HAP (2-Hydroxy-2-methyl-1-phenyl-propan-1-one) and TPO(Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide), aryldiazonium salts,triarylsulfonium salts, ferrocenium salts, diaryliodonium salts.
 13. Themethod of claim 9 wherein the diffuser is opal glass, white glass, oracrylate with light diffusing additives.
 14. The method of claim 1further comprising spinning the formed lens and applying a hard coating.15. The method of claim 1 wherein the exposure time is a single periodof time, and wherein the irradiation pattern is a single irradiationpattern that coincides with forming a lens having the lens prescription.16. A method for creating a lens, the method comprising: receiving inputinformation including a lens prescription; calculating creationinstructions based on the input information, the creation instructionsincluding: 1) an irradiation pattern, and 2) an exposure time to use alight transmission of the irradiation pattern to form a lens having thelens prescription; initiating the light transmission of the irradiationpattern from a light source through a diffuser into a container holdingresin held within a substrate, wherein each point in a thickness of theresin sufficient to form the lens is illuminated by at least 10% of anarea of the diffuser; and stopping the light transmission after theexposure time to form the lens, wherein the lens meets the creationinstructions, wherein a single polymerization front has the shape of atarget surface of the lens that meets the creation instructions, whereinthe substrate includes embedded electronic circuits or embedded imageformation systems.
 17. The method of claim 16 wherein the creationinstructions include 3) a resin composition.
 18. A method for creating alens, the method comprising: receiving input information including alens prescription; calculating creation instructions based on the inputinformation, the creation instructions including: 1) an irradiationpattern, and 2) an exposure time to use a light transmission of theirradiation pattern to form a lens having the lens prescription;initiating the light transmission of the irradiation pattern from alight source through a diffuser into a container holding resin heldwithin a substrate, wherein each point in a thickness of the resinsufficient to form the lens is illuminated by at least 10% of an area ofthe diffuser; and stopping the light transmission after the exposuretime to form the lens, wherein the lens meets the creation instructions,wherein a single polymerization front has the shape of a target surfaceof the lens that meets the creation instructions, wherein the substrateis polarized or photochromic.
 19. The method of claim 18 wherein thecreation instructions include 3) a resin composition.
 20. A method forcreating a lens, the method comprising: receiving input informationincluding a lens prescription; calculating creation instructions basedon the input information, the creation instructions including: 1) anirradiation pattern, and 2) an exposure time to use a light transmissionof the irradiation pattern to form a lens having the lens prescription;initiating the light transmission of the irradiation pattern from alight source through a diffuser into a container holding resin heldwithin a substrate, wherein each point in a thickness of the resinsufficient to form the lens is illuminated by at least 10% of an area ofthe diffuser; and stopping the light transmission after the exposuretime to form the lens, wherein the lens meets the creation instructions,wherein a single polymerization front has the shape of a target surfaceof the lens that meets the creation instructions, wherein the substrateincludes a convex surface, and the substrate incorporates anantireflective coating or a hard coating treatment on the convexsurface.
 21. The method of claim 20 wherein the creation instructionsinclude 3) a resin composition.
 22. A method for creating a lens, themethod comprising: receiving input information including a lensprescription; calculating creation instructions based on the inputinformation, the creation instructions including: 1) an irradiationpattern, and 2) an exposure time to use a light transmission of theirradiation pattern to form a lens having the lens prescription;initiating the light transmission of the irradiation pattern from alight source through a diffuser into a container holding resin heldwithin a substrate, wherein each point in a thickness of the resinsufficient to form the lens is illuminated by at least 10% of an area ofthe diffuser; and stopping the light transmission after the exposuretime to form the lens, wherein the lens meets the creation instructions,wherein the lens includes the substrate and the thickness of theilluminated resins.
 23. The method of claim 22 wherein the creationinstructions include 3) a resin composition.